JP6424780B2 - Dynamic quantity sensor - Google Patents

Description

  The present invention relates to a mechanical quantity sensor having a thin portion which is displaced according to a mechanical quantity such as pressure.

  Conventionally, the following pressure sensors have been proposed as this type of dynamic quantity sensor (see, for example, Patent Document 1).

  Specifically, in the pressure sensor, the second substrate is bonded to the first substrate. Then, in the first substrate, a concave portion forming a thin portion is formed on the one surface side from the other surface opposite to the one surface to be bonded to the second substrate, and a gauge in which the resistance value changes according to the pressure in the thin portion A resistance is formed.

  Further, in the second substrate, a recess is formed in a portion of the one surface to be bonded to one surface of the first substrate facing the recess. The recessed portion constitutes a reference pressure chamber as a sealed space with the first substrate, and a gauge resistance is sealed in the reference pressure chamber.

  In such a pressure sensor, the thin-walled portion of the first substrate is configured as a diaphragm that is displaced according to the pressure. Then, when pressure is applied to the thin-walled portion, the thin-walled portion is displaced and the resistance value of the gauge resistance changes, so that an electrical signal corresponding to the resistance value is output as a sensor signal.

  Such a pressure sensor is manufactured by forming a recess and a gauge resistor in the first substrate and forming a recess in the second substrate, and then bonding the first substrate and the second substrate together.

JP, 2012-195442, A

  However, in the pressure sensor, the thin portion at the depressed portion in the second substrate is applied when the pressure in the sealing space, the molding pressure at the time of bonding the two substrates, or when assembling the sensor to the measuring member It is easily deformed in the thickness direction of the substrate due to pressure or the like, and is easily damaged.

  Therefore, it is required to improve the mechanical strength of the thin-walled portion due to the depression in the second substrate. Here, simply, in order to thicken the thin portion of the second substrate due to the depression portion, the entire second substrate may be thick. However, in this case, the physical size in the thickness direction of the second substrate in the pressure sensor is increased, which is not preferable.

  The present invention has been made in view of the above problems, and a pressure sensor in which a first substrate having a thin portion and a second substrate having a recess portion at a portion corresponding to the thin portion are bonded to each other. It is an object of the present invention to improve the mechanical strength of the thin-walled portion of the second substrate due to the depression without thickening the second substrate.

In order to achieve the above object, in the invention according to claim 1, a recess (15) having one surface (10a) and the other surface (10b) opposite to the one surface and constituting a thin-walled portion (15a) on one surface side Has a first substrate (10) formed on the other surface side, and one surface (20a) joined to one surface of the first substrate, and in a portion opposite to the recess in one surface, between the first substrate and And a second substrate (20) having a recess (20c) forming a sealed space (30).
At the bottom of the recess, a beam (40) is provided to suppress deformation of the thin portion of the second substrate due to the recess in the thickness direction of the second substrate. A sensor is provided.

  According to this, even if the thin-walled portion of the second substrate is not thickened, deformation of the thin-walled portion in the thickness direction is suppressed by the beam, so it is not necessary to thicken the second substrate. . Therefore, according to the present invention, it is possible to improve the mechanical strength of the thin portion of the second substrate due to the recess without thickening the second substrate.

  Here, as in the invention described in claim 2, in the dynamic quantity sensor according to claim 1, further, in the bottom of the depressed portion, in the thickness direction of the first substrate of the thin portion in the first substrate Preferably, a projection (50) is provided as a stopper for suppressing excessive deformation of the valve.

  According to this, when the thin portion of the first substrate is deformed in the thickness direction toward the second substrate due to pressure application or the like, the thin portion is abutted against the protrusion and excessive deformation is stopped, so damage to the thin portion It is also easier to prevent.

  In addition, the code | symbol in the parenthesis of each means described in the claim and this column is an example which shows the correspondence with the specific means as described in embodiment mentioned later.

It is a schematic sectional drawing which shows the pressure sensor as a dynamic quantity sensor concerning 1st Embodiment of this invention. It is a schematic plan view which shows the planar structure of the hollow part of the 2nd board | substrate in the pressure sensor shown by FIG. It is sectional drawing which shows typically the vicinity of the penetration electrode part in the 2nd board | substrate for showing the effect in said 1st Embodiment. It is a schematic plan view which shows the planar structure of the hollow part of the 2nd board | substrate as a 1st modification in said 1st Embodiment. It is a schematic plan view which shows the planar structure of the hollow part of the 2nd board | substrate as a 2nd modification in said 1st Embodiment. It is a schematic plan view which shows the planar structure of the hollow part of the 2nd board | substrate in the pressure sensor as a 1st example concerning 2nd Embodiment of this invention. It is a schematic plan view which shows the plane structure of the hollow part of the 2nd board | substrate in the pressure sensor as a 2nd example concerning the said 2nd Embodiment.

  Hereinafter, an embodiment of the present invention will be described based on the drawings. In the drawings, the same reference numerals are given to the same or equivalent parts in the drawings in order to simplify the description.

First Embodiment
A dynamic quantity sensor according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2. In the present embodiment, it is assumed that the dynamic quantity sensor is mounted on a vehicle such as an automobile, for example, and is applied as a pressure sensor for driving various electronic devices for the vehicle.

  As shown in FIG. 1, in the pressure sensor of the present embodiment, a second substrate 20 as a cap is bonded to a first substrate 10 as a sensor substrate.

  The first substrate 10 is configured using an SOI (Silicon on Insulator) substrate 14 in which a support substrate 11, an insulating film 12, and a semiconductor layer 13 are sequentially stacked and formed into a rectangular plate shape. The surface of the semiconductor layer 13 opposite to the insulating film 12 is the one surface 10 a of the first substrate 10, and the surface of the support substrate 11 opposite the insulating film 12 is the other surface 10 b of the first substrate 10. It is assumed.

  In the present embodiment, the SOI substrate 14 corresponds to the semiconductor substrate constituting the first substrate 10. Further, a silicon substrate is used as the support substrate 11 and the semiconductor layer 13, and an oxide film (SiO 2) or the like is used as the insulating film 12. In the first substrate 10, the concave portion 15 is formed on the other surface 10b side, so that a thin portion 15a is formed on the one surface 10a side as a bottom portion of the concave portion 15.

  Specifically, a recess 15 having a rectangular cross section reaching the insulating film 12 is formed on the support substrate 11 at one end (the end on the right side of the drawing in FIG. 1) to form a thin portion 15a. In the present embodiment, the thin portion 15 a is configured by the insulating film 12 and the semiconductor layer 13 which are the bottom of the recess 15.

  In the present embodiment, the bottom surface of the concave portion 15, that is, the thin portion 15a has a rectangular planar shape. Then, in the semiconductor layer 13 of the thin portion 15a, a gauge resistor 16 whose resistance value changes with pressure is formed as a sensing element that performs sensing. The gauge resistor 16 is formed of a diffusion resistor or the like.

  Then, in the semiconductor layer 13, the wiring layer 17 is formed on the other end side (the end side on the left side of the drawing in FIG. 1) than the thin portion 15 a. The wiring layer 17 is electrically connected to the connection point of each of the gauge resistors 16 in another cross section different from that in FIG. 1 by being appropriately routed in the semiconductor layer 13.

  The second substrate 20 is a silicon substrate 21 having one surface 21 a and the other surface 21 b, an insulating film 22 formed on one surface 21 a of the silicon substrate 21 and having a thermal expansion coefficient different from that of the silicon substrate 21 and the semiconductor layer 13 And the insulating film 23 formed on the other surface 21 b of the semiconductor laser 21. The insulating film 22 on the side of the first surface 21 a of the silicon substrate 21 is bonded to the semiconductor layer 13 constituting the first surface 10 a of the first substrate 10.

  The insulating film 22 formed on one surface 21 a of the silicon substrate 21 and the insulating film 23 formed on the other surface 21 b of the silicon substrate 21 are made of an insulating material such as an oxide film (SiO 2).

  In the present embodiment, the surface of the insulating film 22 on the one surface 21 a side of the silicon substrate 21 opposite to the silicon substrate 21 is the one surface 20 a of the second substrate 20 and the other surface 21 b of the silicon substrate 21. The surface of the insulating film 23 opposite to the silicon substrate 21 is the other surface 20 b of the second substrate 20.

  Further, in the present embodiment, in the second substrate 20, the silicon substrate 21 corresponds to a substrate having the one surface 21a facing the first substrate 10, and the insulating film 22 on the one surface 20a side corresponds to a bonding member. .

  In the second substrate 20, a recess 20c is formed in a portion of the silicon substrate 21 facing the thin portion 15a of the first substrate 10. The recess 20 c is formed by etching the one surface 21 c side of the silicon substrate 21 or the like. The recess 20c will be described in detail later with reference to FIG.

  Thus, a reference pressure chamber 30 is formed between the first substrate 10 and the second substrate 20. The reference pressure chamber 30 corresponds to a sealing space that seals the gauge resistor 16 by the space between the first substrate 10 and the recess 20 c. For example, when the first substrate 10 and the second substrate 20 are bonded under vacuum conditions, the reference pressure chamber 30 is vacuum pressure.

  In addition, as shown in FIG. 1, the second substrate 20 penetrates from one surface 20 a of the second substrate 20 to the other surface 20 b opposite to the one surface, that is, the second substrate 20 in the thickness direction A plurality of penetrating electrode portions 24 penetrating are formed.

  Specifically, each through electrode unit 24 includes a through hole 24 a which penetrates the silicon substrate 21 and the insulating films 22 and 23 to expose the wiring layer 17. Each through electrode portion 24 includes the through hole 24 a, the insulating film 24 b formed on the wall surface of the through hole 24 a, and the through electrode formed on the insulating film 24 b and electrically connected to the wiring layer 17. And 24c.

  A portion connected to the through electrode 24c and disposed on the insulating film 23 is a pad portion 24d electrically connected to an external circuit through a wire or the like. In the through electrode portion 24, for example, tetraethyl orthosilicate (TEOS) or the like is used as the insulating film 24b, and as the through electrode 24c and the pad portion 24d, for example, aluminum or the like is used.

  Here, the depressed portion 20c of the second substrate 20 will be further described with reference to FIG. 2 in addition to FIG. In FIG. 2 and FIGS. 4 and 5 described later, the outline of the thin portion 15a of the first substrate 10, that is, the outline of the bottom of the recess 15 is indicated by a broken line as a reference.

  As shown in FIGS. 1 and 2, a beam 40 is provided at the bottom of the recess 20c. In the example shown in FIG. 2, the beam 40 projects from the bottom at the periphery of the bottom of the recess 20 c and is configured as a convex portion disposed in a rectangular frame shape. And here, the beam 40 is made into the rectangular frame shape along each side of the bottom part of the hollow part 20c which makes a rectangular shape.

  The beam 40 suppresses deformation of the thin portion of the second substrate 20 due to the recess 20 c in the thickness direction of the second substrate 20. Furthermore, the beam 40 is configured as a reinforcing portion that improves the mechanical strength against pressure applied in the thickness direction for the thin portion of the second substrate 20 due to the recess 20c.

  Further, in the present embodiment, as shown in FIG. 1 and FIG. 2, a projection 50 as a stopper is further provided at the bottom of the recess 20 c separately from the beam 40. In the example shown in FIG. 2, the protrusion 50 is provided in a portion corresponding to the central portion of the thin portion 15 a of the first substrate 10 in the bottom of the recess 20 c. Further, as described above, the beam 40 is provided on the periphery of the protrusion 50 in the bottom of the recess 20 c.

  The protrusion 50 also protrudes from the bottom of the recess 20c, and is excessive when the thin portion 15a of the first substrate 10 is deformed toward the second substrate 20 in the thickness direction of the first substrate 10. It functions as a stopper that suppresses deformation. Specifically, when the thin-walled portion 15a is excessively deformed, the thin-walled portion 15a comes into contact with the projection 50 and is not deformed further.

  Furthermore, when the thin-walled portion 15a undergoes excessive deformation, it is the projection 50 that hits first, and hitting the beam 40 is suppressed. Therefore, in terms of the projecting height, it can be said that it is preferable that the protrusion 50 and the beam 40 be equal or that the protrusion 50 be larger than the beam 40.

  Such a beam 40 and the projection 50 are formed together with the recessed portion 20 c by etching the semiconductor portion of the second substrate 20, that is, the silicon substrate 21 when forming the recessed portion 20 c on the one surface 20 a of the second substrate 20. Ru. In the case of etching the recess 20c, for example, the etching depth may be selectively changed with respect to the portion other than the portion of the beam 40 or the protrusion 50 in the recess 20c.

  Also, as described above, the thin portion 15a of the first substrate 10 is provided with a gauge resistor 16 as a sensing element. Then, as shown in FIG. 1, the wiring layer 17 is electrically connected to the gauge resistor 16 on the first surface 10a side of the first substrate 10, that is, the semiconductor layer 13, and portions other than the thin portion 15a to the thin portion 15a. It is supposed to be extended to

  Also, as described above, as shown in FIG. 1, the through electrode portion 24 is provided in a portion of the second substrate 20 other than the recessed portion 20 c and penetrates from the one surface 20 a to the other surface 20 b of the second substrate 20. Thus, the wiring layer 17 is electrically connected. Here, as shown in FIG. 1, the through electrode portion 24 has a conical shape whose diameter decreases from the other surface 20 b of the second substrate 20 toward the one surface 20 a.

  In such a pressure sensor, the thin portion 15a of the first substrate 10 is configured as a diaphragm that is displaced according to pressure. Then, when pressure is applied to the thin portion 15a from the other surface 10b side of the first substrate 10, the thin portion 15a is displaced and the resistance value of the gauge resistor 16 changes, so an electrical signal according to the resistance value Is output as a sensor signal.

  Such a pressure sensor is manufactured similarly to the conventional one shown in the above-mentioned patent documents 1 grade. Specifically, the recess 15 is formed in the first substrate 10 by etching, and the gauge resistor 16 and the wiring layer 17 are formed by the semiconductor process.

  On the other hand, while forming the recessed part 20c, the beam 40, and the protrusion 50 by an etching in the 2nd board | substrate 20, a penetration electrode part 24 grade | etc., Is formed by a semiconductor process. Then, the first substrate 10 and the second substrate 20 are attached to each other. Thereby, a pressure sensor is manufactured.

  By the way, according to the present embodiment, even if the thin portion by the depressed portion 20c in the second substrate 20 is not thickened, the thin portion can be restrained from being deformed in the thickness direction by the beam 40. It becomes unnecessary to make 20 thick. Therefore, according to the present embodiment, it is possible to improve the mechanical strength of the thin portion of the second substrate 20 due to the depression 20c without thickening the second substrate 20.

  Further, according to the present embodiment, a projection 50 as a stopper is further provided at the bottom of the recess 20c. Therefore, when the thin portion 15a of the first substrate 10 is deformed in the thickness direction toward the second substrate 20 due to pressure application or the like, excessive deformation is prevented by the thin portion 15a coming into contact with the protrusion 50. It also helps to prevent damage.

  Further, according to the present embodiment, the protrusion 50 is provided at a portion corresponding to the central portion of the thin portion 15a of the first substrate 10 at the bottom of the recess 20c, and the beam is provided on the periphery of the protrusion 50. ing.

  In the thin portion 15a of the first substrate 10, it is the central portion that is most likely to be displaced in the thickness direction by pressure application or the like. Therefore, if the protrusion 50 is made to face the central portion of the thin portion 15a as described above, excessive deformation can be stopped at the central portion of the thin portion 15a that is likely to be maximally displaced, and damage to the thin portion 15a is prevented. Desirable in terms of

  Further, as described above, even if the thin portion of the second substrate 20 due to the recess 20c is not thickened, the beam 40 can suppress deformation in the thickness direction, so the second substrate 20 can be thickened. It becomes unnecessary to make the whole second substrate 20 thinner by the effect of the beam 40.

  Then, in this case, it is possible to reduce the size of the sensor in the thickness direction in which the first substrate 10 and the second substrate 20 are combined, that is, in the stacking direction of the first substrate 10 and the second substrate 20.

  Further, as shown in FIG. 3, when the entire thickness of the second substrate 20 is reduced from the thickness T1 to the thickness T2, the conical through electrode portion 24 is positioned at the other surface 20 b of the second substrate 20. The diameter of the portion to be cut can be reduced from the diameter D1 to the diameter D2.

  That is, when the entire second substrate 20 is thinned, the planar size of the through electrode portion 24 can be reduced as viewed from the other surface 20 b side of the second substrate 20, and the through electrode in the other surface 20 b of the second substrate 20 There is also an advantage that the space occupied by the part 24 can be reduced.

  Here, with reference to FIG. 4, FIG. 5, the modification of the beam 40 in the bottom part of the hollow part 20c and the protrusion 50 is described. In both FIG. 4 and FIG. 5, the protrusion 50 is provided at a portion corresponding to the central portion of the thin portion 15a of the first substrate 10 at the bottom of the recess 20c, and the beam is provided on the peripheral side of the protrusion 50. .

  Here, in the first modified example shown in FIG. 4, the beam 40 is configured as a convex portion disposed in a rectangular frame shape, but the beam 40 of this example is different from that of FIG. 2 described above. , And about 45 ° around the projection 50. Further, in the second modified example shown in FIG. 5, the beams 40 are in the shape of two bars along the two opposing sides of the bottom of the rectangular recess 20 c.

  The effects of the beam 40 and the protrusion 50 in the above-described embodiment can be exhibited also by the examples shown in FIGS. 4 and 5. Although the protrusion 50 is provided at a position corresponding to the central portion of the thin portion 15a of the first substrate 10, the protrusion 50 may be formed of a plurality of aggregates instead of one. .

  Furthermore, the arrangement position, the shape, and the number of the beams 40 and the protrusions 50 are not limited to these modified examples, and any design change can be made as long as the effects of the above-described embodiment can be obtained. Of course there is one thing. However, as described above, it is preferable that the protrusion 50 be provided at a portion corresponding to the central portion of the thin portion 15 a of the first substrate 10 in any case.

  Further, in FIGS. 2, 4 and 5, the planar size of the recess 20 c of the second substrate 20 is one size larger than the planar size of the thin portion 15 a of the first substrate 10. However, the planar size of the thin portion 15 a of the first substrate 10 may be equal to or one size larger than the planar size of the recess 20 c of the second substrate 20.

Second Embodiment
A second embodiment of the present invention will be described with reference to FIGS. 6 and 7, focusing on differences from the first embodiment. In the first embodiment, as shown in FIG. 1 and FIG. 2, the projection 50 is provided at the bottom of the recess 20 c separately from the beam 40.

  On the other hand, as shown in FIGS. 6 and 7, in the present embodiment, the beam 40 and the projection 50 are formed as a continuous integral member that protrudes from the bottom surface (that is, the bottom) of the recess 20c. There is.

  In the first example shown in FIG. 6, this integral member has a cruciform pattern in which four tips are located on each side of the bottom of the rectangular recess 20c. Further, in the second example shown in FIG. 7, this integral member has a cruciform pattern in which four tip portions are located at each corner of the rectangular recess 20c.

  Then, in an integral member forming a cross-shaped pattern in each example, the cross portion of the cross located at the portion corresponding to the central portion of the thin portion 15a constitutes the protrusion 50, and the bar-like portion extending from the cross portion is a beam It consists of 40. That is, it can be said that a configuration in which a part of the beam 40 doubles as the protrusion 50 is realized.

(Other embodiments)
In order to exert the effect of improving the mechanical strength of the thin portion of the second substrate 20 due to the recess 20c without thickening the second substrate 20, at least the beam 40 is sufficient, and the protrusion 50 is There may be no configuration.

  The beams 40 and the protrusions 50 are not limited to being formed of the silicon substrate 21 by etching the silicon substrate 21 itself of the second substrate 20, and may be formed of a material different from the silicon substrate 21. It may be For example, the insulating film, such as a resin film, a silicon oxide film, or a silicon nitride film, may be selectively formed separately on the bottom of the recess 20 c to form the beam 40 or the projection 50.

  In each of the above embodiments, the thin portion 15a of the first substrate 10 is configured as a diaphragm that performs pressure detection, whereby a pressure sensor as a dynamic quantity sensor is configured. However, the dynamic quantity sensor is not limited to the pressure sensor, and may be an acceleration sensor or the like. In this case, for example, the thin-walled portion 15a of the first substrate 10 may be formed by patterning a comb-tooth structure constituting a movable electrode or a fixed electrode as a sensing element.

  Moreover, this invention is not limited to above-described embodiment, In the range described in the claim, it can change suitably. Moreover, said each embodiment is not mutually unrelated and can be combined suitably unless the combination is obviously impossible, and said each embodiment is limited to said example of illustration. Absent. Further, in each of the above-described embodiments, it is needless to say that the elements constituting the embodiment are not necessarily essential except when clearly indicated as being essential and when it is considered to be obviously essential in principle. Yes. Further, in the above embodiments, when numerical values such as the number, numerical value, amount, range, etc. of constituent elements of the embodiment are mentioned, it is clearly indicated that they are particularly essential and clearly limited to a specific number in principle. It is not limited to the specific number except when it is done. Further, in the above embodiments, when referring to the shape, positional relationship, etc. of the component etc., unless otherwise specified or in principle when limited to a specific shape, positional relationship, etc., the shape, etc. It is not limited to the positional relationship and the like.

10 first substrate 10a first surface of first substrate 10b second surface of first substrate 15 recess 15a thin portion 20 second substrate 20a first surface of second substrate 20c recessed portion 30 sealing space 40 beam

Claims (7)

A first substrate (one surface (10a) and the other surface (10b) opposite to the one surface, and a recess (15) forming the thin portion (15a) on the one surface is formed on the other surface 10) and
A recessed portion having a surface (20a) to be bonded to one surface of the first substrate, and forming a sealed space (30) between the first substrate and a portion facing the recess in the one surface (20a) 20c) and a second substrate (20) formed thereon,
A mechanical quantity sensor provided with a beam (40) for suppressing deformation of a thin portion of the second substrate due to the recess in the thickness direction of the second substrate at the bottom of the recess .   Furthermore, a projection (50) is provided at the bottom of the recessed portion as a stopper for suppressing excessive deformation of the thin portion of the first substrate in the thickness direction of the first substrate. Mechanical quantity sensor described in. The protrusion is provided at a position corresponding to a central portion of the thin-walled portion of the first substrate in a bottom portion of the recessed portion,
The mechanical quantity sensor according to claim 2, wherein the beam is provided on a peripheral side of the protrusion in a bottom portion of the recessed portion.   The mechanical quantity sensor according to claim 2 or 3, wherein the beam and the projection are formed as a continuous integral member projecting from a bottom surface of the recess. The thin portion is provided with a sensing element (16) for sensing.
A wiring layer (17) electrically connected to the sensing element and extending from the thin portion to a portion other than the thin portion is provided on one surface side of the first substrate,
A penetrating electrode portion which penetrates from one surface of the second substrate to the other surface (20b) opposite to the one surface and electrically connected to the wiring layer in a portion other than the recessed portion in the second substrate (24) is provided,
The dynamic quantity sensor according to any one of claims 1 to 4, wherein the through electrode portion has a conical shape whose diameter decreases from the other surface of the second substrate toward one surface of the second substrate. . The second substrate is a substrate (21) having a surface (21a) facing the first substrate;
The second is formed on one surface of the substrate constituting the substrate (21) (21a), the second said substrate (21) constituting the substrate and the first joint made of a different material substrate and the thermal expansion coefficient A member (22), and
The bonding member is bonded to one surface of the first substrate,
The dynamic quantity sensor according to any one of claims 1 to 5, wherein the recess is formed in the substrate (21) constituting the second substrate . The first substrate is a semiconductor substrate in which a support substrate (11), an insulating film (12), and a semiconductor layer (13) are sequentially stacked.
The recess is formed from the surface of the support substrate opposite to the insulating film to the insulating film,
The dynamic quantity sensor according to any one of claims 1 to 6, wherein the thin portion is constituted by the insulating film and the semiconductor layer which constitute a bottom surface of the recess.

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